U.S. patent number 7,678,056 [Application Number 11/904,776] was granted by the patent office on 2010-03-16 for array rotation for ultrasound catheters.
This patent grant is currently assigned to Siemens Medical Solutions USA, Inc.. Invention is credited to Lex J. Garbini, Jian Hua Mo, Walter T. Wilser.
United States Patent |
7,678,056 |
Wilser , et al. |
March 16, 2010 |
Array rotation for ultrasound catheters
Abstract
A transducer array is connected with a catheter housing. As the
transducer array is rotated, the catheter housing also rotates. As
a result, at least a portion of the catheter housing twists about a
longitudinal axis. By applying rotation in a controlled way, such
as with a motor, a plurality of two-dimensional images for
three-dimensional reconstruction may be obtained. The rotation of
the catheter housing may limit the total amount of rotation of the
array, such as rotating the array through a 90 degree or less
amount of rotation about the longitudinal axis. The housing of the
catheter is formed with a soft section. The softer material allows
for a greater amount or increased ease for twisting the
catheter.
Inventors: |
Wilser; Walter T. (Cupertino,
CA), Garbini; Lex J. (San Gregorio, CA), Mo; Jian Hua
(Milpitas, CA) |
Assignee: |
Siemens Medical Solutions USA,
Inc. (Malvern, PA)
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Family
ID: |
36571324 |
Appl.
No.: |
11/904,776 |
Filed: |
September 27, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080027327 A1 |
Jan 31, 2008 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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11012389 |
Dec 14, 2004 |
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Current U.S.
Class: |
600/463; 600/466;
600/462; 600/459; 600/439; 600/437 |
Current CPC
Class: |
A61B
8/12 (20130101); A61B 8/13 (20130101); A61B
8/4461 (20130101); A61B 8/445 (20130101) |
Current International
Class: |
A61B
8/14 (20060101) |
Field of
Search: |
;600/407,408,437-463
;601/2-4 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Le; Long V
Assistant Examiner: Cattungal; Sanjay
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a divisional of U.S. patent application No.
11/012,389, filed Dec. 14, 2004.
Claims
We claim:
1. A method for scanning a volume with an ultrasound catheter, the
method comprising: (a) providing an ultrasound catheter having a
housing, the housing comprising a first portion having a transducer
array, a third portion having a motor, and a second flexible
portion between the first and third portions; (b) rotating a
transducer array about a longitudinal axis of the ultrasound
catheter; (c) rotating the first portion of the housing of the
ultrasound catheter about the longitudinal axis with the transducer
array a substantially same amount; (d) twisting the second portion
of the housing about the longitudinal axis in response to the
rotation of the transducer array, the first portion or combinations
thereof; (e) maintaining the third portion of the housing
substantially free of the twisting and rotation of the second and
first portions during the twisting and rotation of the second and
first portions; (f) scanning with the ultrasound transducer along a
plurality of planes rotated about the longitudinal axis in response
to (b) and (c); and (g) generating an image representing the volume
as a function of data along the plurality of planes.
2. The method of claim 1 wherein (b) and (c) comprise rotating a
shaft within the housing, the shaft connected with the first
portion, the transducer array or both the first portion and the
transducer array.
3. The method of claim 1 wherein (b) and (c) comprise rotation in
response to a motor in the third portion.
4. The method of claim 1 wherein (e) comprises maintaining the
third portion, the third portion being spaced away from a handle
and adjacent to a tip portion.
5. The method of claim 1 wherein (d) comprises providing the second
portion as softer than the third portion.
6. The method of claim 1 wherein (d) comprises rotating a distal
portion of the second portion to a greater extent than a proximal
portion of the second portion about the longitudinal axis.
7. The method of claim 1 wherein (b) and (c) comprise always
rotating less than 360 degrees.
8. The method of claim 1 wherein (b) and (c) comprise rotating only
within an arc about the longitudinal axis of 30 degrees.
9. The method of claim 8 wherein (d) comprises twisting a first
direction less than 15 degrees at a greatest extent of twisting and
twisting in an opposite, second direction less than 15 degrees at
the greatest extent of twisting, the housing free of twisting at 0
degrees.
10. The method of claim 7 further comprising: oscillating the
ultrasound transducer; wherein (d) comprises twisting in opposite
directions in response to the oscillation of the ultrasound
transducer.
11. The method of claim 1 further comprising: converting rotational
motion at a first speed of a motor to lateral motion and the later
motion to rotational motion at a second speed different than the
first speed, the rotational motion at the second speed operable to
rotation the transducer array.
Description
BACKGROUND
The present invention relates to ultrasound imaging with catheters.
In particular, two- or three-dimensional imaging is provided with
an array in a catheter.
In the AcuNav.TM. catheter, a 64 element array of elements extends
along a longitudinal axis of the catheter. The array is positioned
at a tip portion for scanning a two-dimensional region or plane
along the longitudinal axis. Other catheters have been proposed
where one or more elements are rotated within the catheter about
the longitudinal axis to scan in a plane perpendicular to the
axis.
During use, a catheter is inserted within the circulatory system of
the patient. The flexibility along the catheter may vary as a
function of position, such as having a more flexible tip portion
for off-axis bending while guiding the catheter. The catheter is
guided through the circulatory system to position the ultrasound
transducer adjacent to a desired location. Guide wires or rotation
of the entire catheter are used to position the image plane at the
desired location. Various stresses and strains may cause bending
and slight twisting along the catheter. Images are then generated
of the desired location.
By only scanning along a two-dimensional plane, identifying the
desired location may be more difficult. Three-dimensional imaging
has been proposed for more easily identifying a region of interest.
Since catheters are small, such as having a 3 mm diameter, it may
be difficult to position a two-dimensional array within the
catheter. Three-dimensional imaging may be provided by moving the
imaging plane of the one-dimensional array. For example, the
catheter is slowly inserted further or withdrawn from a current
position to create a plurality of cross sectional scans using a
rotating array. However, the imaging plane position for accurate or
higher resolution three-dimensional reconstruction may be
difficult.
BRIEF SUMMARY
By way of introduction, the preferred embodiments described below
include systems, methods and catheters for ultrasound imaging of a
volume. Rotational forces are applied to a transducer array. The
transducer array is connected with the catheter housing. As the
transducer array rotates, the catheter housing also rotates. As a
result, at least a portion of the catheter housing twists about a
longitudinal axis. By applying rotation in a controlled way, such
as with a motor, a plurality of two-dimensional images for
three-dimensional reconstruction may be obtained. The rotation of
the catheter housing may limit the total amount of rotation of the
array, such as rotating the array through a 90 degree or less
amount of rotation about the longitudinal axis. In one embodiment,
the housing of the catheter is formed with a flexible or softer
section. The softer material allows for a greater amount of or
increased ease for twisting the catheter.
In a first aspect, a catheter is provided for ultrasound imaging of
a volume. A transducer section of the catheter houses an ultrasound
transducer array. The array is connected with the transducer
section. A motor is spaced from the transducer section. A drive
shaft connects the motor with the transducer section. A flexible
section of the catheter connects with the transducer section. The
drive shaft extends through at least a portion of the flexible
section. The drive shaft is operable to rotate the ultrasound
transducer array and connected transducer section substantially
about a longitudinal axis of the catheter in response to force from
the motor. The flexible section is operable to twist about the
longitudinal axis in response to the rotation of the transducer
section.
In a second aspect, a system is provided for ultrasound imaging of
a volume. A catheter has a housing. An ultrasound transducer array
of elements is within the housing. A shaft is also within the
housing. The shaft connects with the ultrasound transducer array of
elements. The ultrasound transducer array is operable to rotate
about a longitudinal axis of the housing in response to rotation of
the shaft. The housing is operable to twist from a first portion to
a second portion of the housing. An amount of twist corresponds to
an amount of rotation of the ultrasound transducer array.
In a third aspect, a method is provided for scanning a volume with
an ultrasound catheter. A transducer array is rotated about a
longitudinal axis of the ultrasound catheter. A first portion of a
housing of the ultrasound catheter is also rotated about the
longitudinal axis with the transducer array. The transducer array
and first portion rotate a substantially same amount. A second
portion of a housing twists about the longitudinal axis in response
to the rotation of the transducer array, the first portion of the
housing or both the transducer array and the first portion. A third
portion of the housing of the catheter is maintained substantially
free of the twisting and rotation of the second and first portions
during the twisting and rotation of the second and first
portions.
The present invention is defined by the following claims, and
nothing in this section should be taken as a limitation on those
claims. Further aspects and advantages of the invention are
discussed below in conjunction with the preferred embodiments and
may be later claimed independently or in combination.
BRIEF DESCRIPTION OF THE DRAWINGS
The components and the figures are not necessarily to scale,
emphasis instead being placed upon illustrating the principles of
the invention. Moreover, in the figures, like reference numerals
designate corresponding parts throughout the different views.
FIG. 1 is a side view of one embodiment of a catheter for
ultrasound imaging;
FIG. 2 is a side view of the catheter of FIG. 1 in a twisted
position;
FIG. 3 is a flow chart of one embodiment of a method for ultrasound
imaging with a catheter; and
FIG. 4 is a cross-section view of one embodiment of a motor for
rotating a transducer.
DETAILED DESCRIPTION OF THE DRAWINGS AND PRESENTLY PREFERRED
EMBODIMENTS
An ultrasound transducer stack within a catheter is rotated about
the longitudinal axis of the catheter for positioning a
two-dimensional plane at a desired location or generating a
three-dimensional image. A micro-motor or other source of force
rotates the transducer stack. While a rotating joint may be used,
seals and cable routing of a rotating joint are difficult to
implement in a small space of a typical catheter. To avoid or limit
these difficulties, the catheter housing is radially deflected to
allow rotation of the transducer array. For example, a housing of
low durometer or soft Pebax is provided with a rigid shaft. The
rigid shaft transmits force for rotation of the array. The soft
housing allows twisting of the catheter about the longitudinal
axis.
FIG. 1 shows a system for ultrasound imaging a region or volume
from within a patient. The system includes a catheter 10 and a
controller 24. The controller 24 is positioned outside of, away
from or within the catheter 10. In one embodiment, the controller
24 is positioned within an ultrasound imaging system connected with
the catheter 10.
The catheter 10 is adapted for insertion within a circulatory or
venous system. For example, the catheter 10 is about 5 mm or less
in diameter. Larger or smaller catheters may be used. The catheter
10 includes a sterile or other safe coating for use within a
patient. One or more guide wires or other structures for steering
the catheter 10 may be provided. In other embodiments, the catheter
10 is adapted for insertion through a portal or tube within another
structure, such as a guide catheter. Any now known or later
developed catheter structures may be used, such as providing an
elongated flexible tip with a narrower diameter than the main body
of the catheter 10.
The catheter 10 includes a housing 11, a transducer array 18, a
shaft 20 and a motor 22. Additional, different or fewer components
may be provided, such as providing the motor 22 external to the
housing 11 in a handle. As another example, guide wires, ports,
tubes, circuitry, signal cabling, or other now known or later
developed catheter structure is provided.
The housing 11 includes one or more sections 12, 14, 16. For
example, a transducer section 12 connects to a motor section 16
through a flexible section 14. The transducer section 12
corresponds to a section of the catheter 10 surrounding or
associated with the transducer array 18. Similarly, the motor
section 16 corresponds to a portion of the housing 11 associated
with the motor 22. The transducer and motor sections 12, 16 may be
of any length, such as less than, the same as or greater than the
length of the respective transducer array 18 and motor 22. The
sections 12, 14, 16 are provided at a tip of the catheter 10, such
as a region 1-10 inches in length at a distal portion of the
catheter 10 from a handle. In other embodiments, all, one or more
of the sections has a greater or lesser length. The flexible
section 14 extends over any distance, such as a centimeter, an
inch, inches, or the entire extent of the housing 11 away from the
transducer 18.
In one embodiment, the housing 11 is the same for each of the
different sections 12, 14, 16. For example, each of the sections
12, 14, 16 are formed from a same extruded material, such as a
polymer. Other now known or later developed materials may be used.
In other embodiments, the housing 11 of the catheter 10 varies as a
function of the section 12, 14, 16. In one embodiment, 35 to 25
shore D Pebax, Nylon or Silicone is used. In other embodiments, the
housing 11 of the catheter 10 varies as a function of the section
12, 14, 16. For example, the extrusion process is varied or the
material used for the extrusion is varied as a function of the
sections 12, 14, 16. The flexible section 14 is formed from a
softer material or the same material processed to be softer than
the harder transducer section 12 and/or motor section 16. While
represented as sharp distinctions between the sections 12, 14, 16
by the circumferential lines in FIG. 1, the difference in hardness
may gradually vary between the sections 12, 14, 16. The softer
flexible section 14 provides a lower durometer portion of the
housing 11. In alternative embodiments, the flexible section 14
extends over the motor 22, over all or a portion of the transducer
18 or is separate from both. The motor section 16 and/or the
transducer section 12 may have a same softness or hardness as the
flexible section 14, as each other or be different.
The flexible section 14 is operable to twist about the longitudinal
axis of the catheter 10 in response to rotation of the transducer
section 12 and the transducer 18. FIG. 2 shows the flexible section
14 twisting as compared to the motor section 16 and the transducer
section 12. The transducer 18 and transducer section 12 are shown
rotated by about 45 degrees. Twist lines are shown in the flexible
section 14 associated with the 45 degrees of twisting. The twisting
is shown just by the flexible section 14, but may extend into or
through the motor section 16 and/or transducer section 12. Where
the flexible section 14 is softer or more flexible than other
sections 12, 16, a greater amount of twisting may be provided in
the flexible section 14 than the other sections. The twisting may
occur from a point of first contact of the transducer 18 with the
transducer section 12 through to a point of contact or connection
of the motor 22 to the motor section 16 of the housing 11. Where
the sections have similar flexibility, the amount of twisting in
any one section 12, 14, 16 is based on the length of the
section.
The amount of the twist corresponds to the amount of rotation of
the ultrasound transducer array. For example, where the ultrasound
transducer array is rotated about the longitudinal axis by 8
degrees, 15 degrees, 30 degrees, 45 degrees, 90 degrees, 180
degrees, 270 degrees or other amount, the twist absorbs or is
rotated the same amount from the transducer 18 and the portion of
the transducer section 12 through to the motor 22 and a portion of
the motor section 16. Where the motor 22 or the transducer 18
mounts to the housing spaced away from the motor 22 or the
transducer 18, the mounting location determines the range of twist.
The amount of twist is about the same since the motor 22 and the
transducer 18 connect with the housing 11.
The catheter 10 and associated housing 11 allow for angular
repositioning of the transducer array 18 about the longitudinal
axis by absorbing the rotation through twisting in the catheter 10.
The amount of twisting is more than incidental. The motor 22 and
shaft 20 communicate intentional rotation to the transducer array
18 for rotation about the longitudinal axis. The twisting is in
addition to or other than twisting provided by rotating the
catheter 10 on the handle externally to the patient while the
catheter 10 is within the patient.
The ultrasound transducer 18 is a one-dimensional array of
piezoelectric, membrane or other now known or later developed
acoustic transducers. Multidimensional, such as 1.25, 1.5, 1.75 or
two-dimensional arrays may be used. The transducer array 18
includes a plurality of elements extending along the longitudinal
axis of the catheter 10. The elements may be spaced from the axis
or centered on the axis. As the transducer array 18 rotates about
the longitudinal axis, the face of the transducer associated with
the elements rotates. The imaging plane associated with the
transducer elements also rotates. A mechanical elevation focus is
provided in one embodiment, but an acoustical window without
mechanical focusing may be provided in other embodiments.
The transducer array 18 connects with the transducer section 12 of
the housing 11. For example, the transducer array 18 and its
associated stack, such as backing and matching layers, are pressure
fitted within the transducer section 12. Alternatively, bonding,
riveting, bolts, clips or other attachment mechanisms substantially
fixedly attach the transducer array 18 to the housing 11. As the
ultrasound transducer array 18 or the transducer section 12
rotates, the connection provides for the other of the transducer
section 12 or the transducer array 18 to also rotate. For example,
force supplied by the motor 22 along the shaft 20 applies direct
rotational force to the transducer array 18, the transducer section
12 or both for rotating both. The connection between the transducer
section 12 and the transducer array 18 may be direct or indirect,
such as connecting a backing block or other support structure of
the transducer array 18 directly to or through one or more other
components to the housing 11. The connection may allow some
relative rotation or slippage of the transducer array 18 separate
from or differently from the transducer section 12. For example,
the ultrasound transducer array 18 is operable to rotate a few
degrees within the housing 11 before also forcing the housing 11 at
the transducer section 12 to rotate along the longitudinal
axis.
The motor 22 is a micro motor, such as a servo, piezo, stepper,
micro-brushless DC, or other motor. In one embodiment, the motor 22
is sufficiently small, such as being 3 mm or less in diameter, for
being positioned within the catheter 10. A gear box, such as a
planetary gear head having a 50 to 1 or other gearing reduction, is
provided as part of the motor 22 or separate from the motor 22. The
motor 22 is operable to cause rotation of the shaft 20. In one
embodiment, the shaft 20 and the motor 22 are positioned in a
central position along the longitudinal axis of the catheter 10,
but may be offset from the longitudinal axis. The motor 22 and
associated gearing allow the application of sufficient torque along
the shaft 20 to rotate the transducer array 18 and cause twisting
of the housing 11. The motor 22 is spaced from the ultrasound
transducer array 18 by the shaft 20. In one embodiment, the total
force or torque applied by the motor 22 is matched to the
resistance caused by the twisting of the housing 11 such that the
housing 11 limits the total rotation of the transducer array 18.
For example, the limitation may be 360 degrees or less, such as 90
degrees, 20 degrees, 10 degrees or other limitation on rotation in
a given direction from a neutral position. In alternative
embodiments, the motor 22 supplies sufficient torque but is limited
by control of the motor 22 to avoid undesired wrapping of internal
components about the shaft 20. Rotation beyond 360 degrees may be
provided.
FIG. 4 shows another embodiment of the motor 22. The motor 22 is
connected to a rotational speed reducing mechanism. Reduction in
rotational speed may be useful for low torque or inaccurate angular
positioning motors 22. Part 44 of the shaft 42 is threaded to
translate rotation into lateral motion of the wedges 40. The
lateral motion is translated back into rotation by the matched
wedges 40. As the wedges 40 connected with the threading move
laterally, rotation about the same axis as the shaft 42 is induced
in the matched wedges 40. With fine threads on the first part 44
and rotationally matched wedges 40, the rotation is reduced several
fold, but any amount of reduction may be provided. Alternatively, a
reduction gear box is used. In yet other alternative embodiments,
gearing, cams or other mechanisms convert rotation in one direction
into a wobble or back and forth rotation.
Another embodiment uses a push-pull motor or solenoid. The lateral
motion of the motor 22 is translated into rotation by matched
wedges, gearing, rotational connection or other mechanisms.
The shaft 20 is a drive shaft for transmitting torque from the
motor 22 to the ultrasound transducer array 18. The shaft 20 is
metal, plastic, polymer, fiberglass, resin or other now known or
later developed rigid or semi-rigid material. The shaft 20 extends
through the housing 11, including the flexible section 14. The
shaft 20 is more rigid than the flexible section 14 of the housing
11 so that the torque may be transmitted for rotating the
transducer array 18 while the flexible section 14 twists. The shaft
connects with the motor 22 directly, such as being part of the
motor, or indirectly through gearing. The shaft 20 connects
directly or indirectly to the transducer array 18, the transducer
section 12 or both.
The shaft 20 is operable to rotate the transducer array and the
connected transducer section 12 substantially about the
longitudinal axis of the catheter 10 in response to force from the
motor 22. Using control of the motor 22 or torsional limitations to
the twisting of the housing 11, the ultrasound transducer array 18
is operable to rotate less than 360 degrees in one embodiment, but
greater or lesser limitations on rotations are provided in other
embodiments. The shaft 20 is free of direct connection to the
housing 11 other than for connection with the transducer array 18
or in the flexible section 14. The housing 11 may apply friction to
the shaft 20 or may be spaced away from the shaft 20 using one or
more bearings for allowing rotation.
The controller 24 is a processor, digital signal processor,
application specific integrated circuit, field programmable gate
array, digital circuit, analog circuit or combinations thereof. The
controller 24 is operable to control operation of the motor 22, but
may also be used for controlling other operations, such as transmit
or receive operations for the transducer array 18. The control
wires from the controller 24 extend through the housing 11 for
connection with the motor 22. Separate cabling may be provided for
the transducer array 18 for transmit and receive operation. Since
the rotation of the transducer array 18 is limited, the cabling for
transmit and receive operations may connect directly with the
flexible circuit or the transducer array 18. In one embodiment, the
controller 24 is a mechanical torsional resonant circuit. The
controller 24 is operable to cause the motor 22, shaft 20 and
ultrasound transducer array 18 to rotate or oscillate about the
longitudinal axis over an arch. In one embodiment, the rotation is
over a 270 degree range or less, but greater rotation may be
provided. In one embodiment, the shaft 20 is oscillated to rotate
the transducer array about an arc of 20 degrees or less, such as 10
or fewer degrees to each side of neutral. The housing 11 twists
along the flexible section 14 in opposite direction sequentially in
response to the oscillation. In alternative embodiments, the
controller 24 causes movement or repositioning of the transducer
array 18 without oscillation.
FIG. 3 shows one embodiment of a method for scanning a volume with
an ultrasound catheter. The method uses the catheter 10 and
associated system shown in FIGS. 1 and 2 or a different catheter.
Additional, different or fewer acts may be provided, such as
providing acts 30 and 32 without acts 34, 36, and/or 38.
In act 30, the transducer array and a portion of the housing of the
ultrasound catheter are rotated about the longitudinal axis of the
catheter. Both the portion of the housing and the transducer array
rotate substantially a same amount. Some difference in rotation may
result from a slippage between the transducer array and the
transducer section 12. A shaft within the housing rotates. The
shaft is connected directly or indirectly with the portion of the
housing, the transducer array or both the portion of the housing
and the transducer array to supply torque. In response to a motor
driving the shaft, torque is applied to the transducer array. The
rotational motion is over any range of freedom, such as being less
than 360 degrees. For example, the transducer array is only rotated
within an arc about the longitudinal axis of 30 or fewer degrees.
Other lesser or greater amounts of rotation may be provided.
In act 32, another portion of the housing is twisted about the
longitudinal axis in response to rotation of the transducer array,
the portion of the housing connected to the transducer array or
both. As a result of the twisting, a more distal portion of the
housing rotates further than a more proximal portion of the
housing. For example, a portion of soft or softer material than
other portions of the housing 11 twists to a greater extent closer
to the transducer than a portion further away from the transducer.
The soft portion of the housing absorbs at least some of or all of
the rotation by twisting. The amount of twisting corresponds to the
amount of rotation, such as being the same. In one embodiment, the
greatest extent of twisting is 15 degrees in one direction.
Twisting is provided in an opposite direction for a greatest extent
of 15 degrees, providing at a 30 degrees of arc. The housing is
free of twisting or neutral at zero degrees. Asymmetrical amounts
of twisting may be provided in alternative embodiments.
The twisting is associated with oscillation in one embodiment. An
ultrasound transducer is oscillated about a particular angular
position, such as an angular position associated with the neutral
position of the housing 11. In response to the oscillation of the
ultrasound transducer, twisting is performed in opposite
directions. The twisting is provided along a straight or bent
portion of the catheter. For example, the catheter curves to
conform to a path of a vessel. The twisting is performed along the
longitudinal axis as it curves through the vessel.
In act 34, a portion of the housing of the catheter is maintained
substantially free of twisting during the rotation and twisting of
other portions of the housing. For example, a portion of the
housing adjacent to the motor is maintained relatively free of
twisting where the flexible section between the motor and the
transducer array absorbs the twisting caused by the rotation of the
transducer array. In one embodiment, the motor is positioned within
the catheter spaced away from a handle so that the twisting is
mostly transmitted along a portion of a catheter spaced away from
the handle. Alternatively, twisting is transmitted along a majority
of the catheter, such as to a portion external to the patient.
Where the motor is positioned in a tip portion, the twisting is
substantially, entirely or mostly isolated to the tip portion.
In act 36, the ultrasound transducer is used to scan along a
plurality of planes. Using electronic or mechanical steering,
acoustic energy is sequentially transmitted along a plurality of
scan lines within a plane. Since different scan lines are
transmitted at different times, the plane scanned is a general
plane that may allow for some movement of the transducer array
during the planar scan. A plurality of planes is scanned at
different positions of rotation about the longitudinal axis. Using
controlled movement of the motor or sensing a position of the
transducer array, the relative locations of data associated with
the different planes is obtained. As the transducer array moves or
rotates, additional data is obtained.
In act 38, an image representing a volume is generated as a
function of data acquired along the plurality of planes. Using the
relative position of the scan lines or planes, data is interpolated
or otherwise used to generate a three-dimensional representation.
For example, data is interpolated to a three-dimensional Cartesian
grid and then volume rendering is performed. In alternative
embodiments, one or more two-dimensional images associated with a
same or different plane are generated. For example, the catheter is
positioned adjacent to tissue to be ablated. The transducer array
is then rotated until the desired tissue is identified. Once
identified, the position of the ultrasound transducer relative to
the desired tissue is maintained by ceasing rotation or continuing
rotation to counteract any movement of the catheter.
While the invention has been described above by reference to
various embodiments, it should be understood that many changes and
modifications can be made without departing from the scope of the
invention. It is therefore intended that the foregoing detailed
description be regarded as illustrative rather than limiting, and
that it be understood that it is the following claims, including
all equivalents, that are intended to define the spirit and scope
of this invention.
* * * * *